When a vehicle traveling on a road, particularly on a highway, stops traveling, this vehicle is supposed to promptly give a signal to a following vehicle to notify the following vehicle about the vehicle stop. Use of a reflector or a smoke pot for giving this notification requires a time for preparation, and therefore may be difficult to prevent occurrence of an accident in some cases.
According to a conventional technology currently proposed, a base station side arithmetic device receives a plurality of sets of vehicle information, determines distinction between preceding vehicles and following vehicles, and supplies information to vehicles determined as following vehicles (see Patent Literature 1). According to the technology of Patent Literature 1, a positional relationship between a plurality of vehicles is determined in accordance with positions of the vehicles specified based on acquired GPS position signals.